Four-hundred and thirty years ago, Pope Gregory XIII gave the West a calendar which divided 365 days into what was to be called a "year." With 12 months and 7 days bundled into so-called "weeks," the Gregorian calendar was hailed as a marvel of medieval accuracy. We use it today, despite its occasional messiness — drifting days, leap years and 28-day months.

But as Weekend Edition Sunday notes, some researchers at Johns Hopkins University have devised a different way to count our days — with a leap week every few years to keep the calendar on track. Hats off to USA Today for explaining it all in this nifty graphic.

And, Scientific American says, holidays like Christmas and New Year's Day would always fall on a Sunday. It seems neat and streamlined for our modern age — except maybe to those of us who work on Sundays.